An introduction to the study of the comparative anatomy of animals . dorina. It appears that there are largerand smaller colonies, producing larger and smaller gametes,and also forms intermediate in size between these. It is statedthat the larger gametes never conjugate with one another, butthat the smaller and middle-sized gametes conjugate with thelarger and also with one another. If this is the case, there isat the most the beginning of a differentiation into macrogametesand microgametes, or, as we may say, into female and maleforms, in Pandorina. Digitized by Microsoft® EUDORINA i8i Eudori
An introduction to the study of the comparative anatomy of animals . dorina. It appears that there are largerand smaller colonies, producing larger and smaller gametes,and also forms intermediate in size between these. It is statedthat the larger gametes never conjugate with one another, butthat the smaller and middle-sized gametes conjugate with thelarger and also with one another. If this is the case, there isat the most the beginning of a differentiation into macrogametesand microgametes, or, as we may say, into female and maleforms, in Pandorina. Digitized by Microsoft® EUDORINA i8i Eudorina elegans is not very different in structure fromPandorina. Its colonies, measuring from i to 15 mm. indiameter, are spherical or oval, composed of thirty-two, rarelyof sixteen cells, which differ from those of Pandorina in beingrounded, imbedded at some distance from one another atregular intervals in the colonial envelope, and in the fact thattheir inner ends do not reach to the centre of the colony(fig. 39). The colonies multiply by repeated division of their. Fig. 39- Eudorina elegans. The colony consists of thirty-twoflagellate cells, situated at some distance from oneanother, and enclosed in a common colonial , contractile vacuoles; ?zw, nucleus; am^ amylumbodies ; f«, colonial envelope. (After Stein.) component individual cells, so that daughter colonies areformed much in the same way as in Pandorina. The processof cell-division is somewhat different, but the details need notbe considered here. During the formation of the daughtercolonies the envelope of the mother colony becomes very thin,and eventually it bursts and liberates the daughter coloniesalready provided with their flagella and colonial multiplying for several generations in this manner ageneration of Eudorina colonies appears, the members of which Digitized by Microsoft® 182 COMPARATIVE ANATOMY do not differ in structure from ordinary colonies, but show amarked differentiation i
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